winform treeview checkbox----递归算法利用

在平常开发中，treeview的节点显示checkbox，若节点存在几级时，往往希望，选中父节点后，其子节点都要选中，如何实现勒，请看

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace SmartHome
{
    public partial class TreeViewAndCheckbox : Form
    {
        public TreeViewAndCheckbox()
        {
            InitializeComponent();
            //treeview显示checkbox
            treeView1.CheckBoxes = true;
            TreeViewUtil.ShowTreeViewInfo(treeView1);
            this.treeView1.AfterCheck += new TreeViewEventHandler(treeView1_AfterCheck);

        }


        private void TreeViewAndCheckbox_Load(object sender, EventArgs e)
        {
            treeView1.ExpandAll();
        }

        private void treeView1_AfterCheck(object sender, TreeViewEventArgs e)
        {

            if (e.Action == TreeViewAction.ByMouse)
            {
                textBox1.Text = e.Node.Text;
                if (e.Node.Checked)
                {
                    //取消节点选中状态之后，取消所有父节点的选中状态
                    setChildNodeCheckedState(e.Node, true);

                }
                else
                {
                    //取消节点选中状态之后，取消所有父节点的选中状态
                    setChildNodeCheckedState(e.Node, false);
                    //如果节点存在父节点，取消父节点的选中状态
                    if (e.Node.Parent != null)
                    {
                        setParentNodeCheckedState(e.Node, false);
                    }
                }
            }
        }
        //取消节点选中状态之后，取消所有父节点的选中状态
        private void setParentNodeCheckedState(TreeNode currNode, bool state)
        {
            TreeNode parentNode = currNode.Parent;

            parentNode.Checked = state;
            if (currNode.Parent.Parent != null)
            {
                setParentNodeCheckedState(currNode.Parent, state);
            }
        }
        //选中节点之后，选中节点的所有子节点
        private void setChildNodeCheckedState(TreeNode currNode, bool state)
        {
            TreeNodeCollection nodes = currNode.Nodes;
            if (nodes.Count > 0)
                foreach (TreeNode tn in nodes)
                {

                    tn.Checked = state;
                    setChildNodeCheckedState(tn, state);
                }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int i = 0;
            foreach (TreeNode tn in treeView1.Nodes)
            {
                if (tn.Checked)
                    i++;
                foreach (TreeNode item in tn.Nodes)
                {
                    if (item.Checked)
                    {
                        i++;
                    }
                    foreach (TreeNode nd in item.Nodes)
                    {
                        if (nd.Checked)
                        {
                            i++;
                        }

                    }

                }
                textBox2.Text = i.ToString();

            }

        }

        /// <summary>
        /// 查询treeNode节点下有多少节点被选中（递归实现，不受级数限制）
        /// </summary>
        /// <param name="tv"></param>
        /// <returns></returns>
        private int GetNodeChecked(TreeNode tv)
        {
            int x = 0;
            if (tv.Checked)
            {
                x++;  
            }
            foreach (TreeNode item in tv.Nodes)
            {
               x+= GetNodeChecked(item);

            }
            return x;

        }

        /// <summary>
        /// 查询TreeView下节点被checked的数目
        /// </summary>
        /// <param name="treev"></param>
        /// <returns></returns>
        private int GetTreeViewNodeChecked(TreeView treev)
        {
            int k = 0;
            foreach (TreeNode item in treev.Nodes)
            {
                k += GetNodeChecked(item);
            }
            return k;
        }

        private void button2_Click(object sender, EventArgs e)
        {

            textBox2.Text = GetTreeViewNodeChecked(treeView1).ToString();
        }


    }
}